Provided by: mkvtoolnix_45.0.0-2_amd64 
NAME
mkvmerge - Merge multimedia streams into a Matroska file
SYNOPSIS
mkvmerge [global options] {-o out} [options1] {file1} [[options2] {file2}] [@options-file.json]
DESCRIPTION
This program takes the input from several media files and joins their streams (all of them or just a
selection) into a Matroska file; see the Matroska website[1].
Important
The order of command line options is important. Please read the section "Option order" if you're new
to the program.
Global options
-v, --verbose
Increase verbosity.
-q, --quiet
Suppress status output.
-o, --output file-name
Write to the file file-name. If splitting is used then this parameter is treated a bit differently.
See the explanation for the --split option for details.
-w, --webm
Create a WebM compliant file. This is also turned on if the output file name's extension is "webm".
This mode enforces several restrictions. The only allowed codecs are VP8, VP9 video and Opus, Vorbis
audio tracks. The DocType header item is changed to "webm".
For chapters and tags only a subset of elements are allowed. mkvmerge(1) will automatically remove
all elements not allowed by the specification.
--title title
Sets the general title for the output file, e.g. the movie name.
--default-language language-code
Sets the default language code that will be used for tracks for which no language is set with the
--language option and for which the source container doesn't provide a language.
The default language code is 'und' for 'undefined'.
Segment info handling (global options)
--segmentinfo filename.xml
Read segment information from a XML file. This file can contain the segment family UID, segment UID,
previous and next segment UID elements. An example file and a DTD are included in the MKVToolNix
distribution.
See the section about segment info XML files below for details.
--segment-uid SID1,SID2,...
Sets the segment UIDs to use. This is a comma-separated list of 128-bit segment UIDs in the usual UID
form: hex numbers with or without the "0x" prefix, with or without spaces, exactly 32 digits.
If SID starts with = then its rest is interpreted as the name of a Matroska file whose segment UID is
read and used.
Each file created contains one segment, and each segment has one segment UID. If more segment UIDs
are specified than segments are created then the surplus UIDs are ignored. If fewer UIDs are
specified than segments are created then random UIDs will be created for them.
Chapter and tag handling (global options)
--chapter-language language-code
Sets the ISO 639-2 language code that is written for each chapter entry. Defaults to 'eng'. See the
section about chapters below for details.
This option can be used both for simple chapter files and for source files that contain chapters but
no information about the chapters' language, e.g. MP4 and OGM files.
The language set with this option is also used when chapters are generated with the
--generate-chapters option.
--chapter-charset character-set
Sets the character set that is used for the conversion to UTF-8 for simple chapter files. See the
section about text files and character sets for an explanation how mkvmerge(1) converts between
character sets.
This switch does also apply to chapters that are copied from certain container types, e.g. Ogg/OGM
and MP4 files. See the section about chapters below for details.
--chapter-sync d[,o[/p]]
Adjust the timestamps of the chapters in the following source file by d ms. Alternatively you can use
the --sync option with the special track ID -2 (see section special track IDs).
o/p: adjust the timestamps by o/p to fix linear drifts. p defaults to 1 if omitted. Both o and p can
be floating point numbers.
Defaults: no manual sync correction (which is the same as d = 0 and o/p = 1.0).
This option can be used multiple times for an input file applying to several tracks by selecting
different track IDs each time.
--generate-chapters mode
mkvmerge(1) can create chapters automatically. The following two modes are currently supported:
• 'when-appending' – This mode creates one chapter at the start and one chapter whenever a file is
appended.
Note
mkvmerge(1) requires a video or an audio track to be present in order to be able to determine
when a new file is appended. If one or more video tracks are muxed the first one is used.
Otherwise the first audio track is used.
• 'interval:time-spec' – This mode creates one chapter at fixed intervals given by time-spec. The
format is either the form HH:MM:SS.nnnnnnnnn or a number followed by one of the units 's', 'ms'
or 'us'.
Example: --generate-chapters interval:45s
The names for the new chapters are controlled by the option --generate-chapters-name-template. The
language is set with --chapter-language which must occur before --generate-chapters.
--generate-chapters-name-template template
This sets the name template for chapter names generated by the option --generate-chapters. If the
option is not used then default 'Chapter <NUM:2>' will be used.
There are several variables that can be used in the template that are replaced by their actual values
when a chapter is generated. The string '<NUM>' will be replaced by the chapter number. The string
'<START>' will be replaced by the chapter's start timestamp.
The strings '<FILE_NAME>' and '<FILE_NAME_WITH_EXT>' are only filled when generating chapters for
appended files. They will be replaced by the appended file's name wihtout respectively with its
extension. Note that only the file's base name and extension are inserted, not its directory or drive
components.
You can specify a minimum number of places for the chapter number with '<NUM:places>', e.g.
'<NUM:3>'. The resulting number will be padded with leading zeroes if the number of places is less
than specified.
You can control the format used by the start timestamp with <START:format>. The format defaults to
'%H:%M:%S' if none is given. Valid format codes are:
• %h – hours
• %H – hours zero-padded to two places
• %m – minutes
• %M – minutes zero-padded to two places
• %s – seconds
• %S – seconds zero-padded to two places
• %n – nanoseconds with nine places
• %<1-9>n – nanoseconds with up to nine places (e.g. three places with %3n)
--cue-chapter-name-format format
mkvmerge(1) supports reading CUE sheets for audio files as the input for chapters. CUE sheets
usually contain the entries PERFORMER and TITLE for each index entry. mkvmerge(1) uses these two
strings in order to construct the chapter name. With this option the format used for this name can be
set.
If this option is not given then mkvmerge(1) defaults to the format '%p - %t' (the performer,
followed by a space, a dash, another space and the title).
If the format is given then everything except the following meta characters is copied as-is, and the
meta characters are replaced like this:
• %p is replaced by the current entry's PERFORMER string,
• %t is replaced by the current entry's TITLE string,
• %n is replaced by the current track number and
• %N is replaced by the current track number padded with a leading zero if it is < 10.
--chapters file-name
Read chapter information from the file file-name. See the section about chapters below for details.
--global-tags file-name
Read global tags from the file file-name. See the section about tags below for details.
General output control (advanced global options)
--track-order FID1:TID1,FID2:TID2,...
This option changes the order in which the tracks for an input file are created. The argument is a
comma separated list of pairs IDs. Each pair contains first the file ID (FID1) which is simply the
number of the file on the command line starting at 0. The second is a track ID (TID1) from that file.
If some track IDs are omitted then those tracks are created after the ones given with this option
have been created.
--cluster-length spec
Limit the number of data blocks or the duration of data in each cluster. The spec parameter can
either be a number n without a unit or a number d postfixed with 'ms'.
If no unit is used then mkvmerge(1) will put at most n data blocks into each cluster. The maximum
number of blocks is 65535.
If the number d is postfixed with 'ms' then mkvmerge(1) puts at most d milliseconds of data into each
cluster. The minimum for d is '100ms', and the maximum is '32000ms'.
mkvmerge(1) defaults to putting at most 65535 data blocks and 5000ms of data into a cluster.
Programs trying to find a certain frame can only seek directly to a cluster and have to read the
whole cluster afterwards. Therefore creating larger clusters may lead to imprecise or slow seeking.
--no-cues
Tells mkvmerge(1) not to create and write the cue data which can be compared to an index in an AVI.
Matroska files can be played back without the cue data, but seeking will probably be imprecise and
slower. Use this only if you're really desperate for space or for testing purposes. See also option
--cues which can be specified for each input file.
--clusters-in-meta-seek
Tells mkvmerge(1) to create a meta seek element at the end of the file containing all clusters. See
also the section about the Matroska file layout.
--no-date
By default mkvmerge(1) sets the "date" segment information field to the time & date when multiplexing
started. With this option that field is not written at all.
--disable-lacing
Disables lacing for all tracks. This will increase the file's size, especially if there are many
audio tracks. This option is not intended for everyday use.
--enable-durations
Write durations for all blocks. This will increase file size and does not offer any additional value
for players at the moment.
--disable-track-statistics-tags
Normally mkvmerge(1) will write certain tags with statistics for each track. If such tags are already
present then they will be overwritten. The tags are BPS, DURATION, NUMBER_OF_BYTES and
NUMBER_OF_FRAMES.
Enabling this option prevents mkvmerge(1) from writing those tags and from touching any existing tags
with same names.
--timestamp-scale factor
Forces the timestamp scale factor to factor. Valid values are in the range 1000..10000000 or the
special value -1.
Normally mkvmerge(1) will use a value of 1000000 which means that timestamps and durations will have
a precision of 1ms. For files that will not contain a video track but at least one audio track
mkvmerge(1) will automatically chose a timestamp scale factor so that all timestamps and durations
have a precision of one audio sample. This causes bigger overhead but allows precise seeking and
extraction.
If the special value -1 is used then mkvmerge(1) will use sample precision even if a video track is
present.
File splitting, linking, appending and concatenation (more global options)
--split specification
Splits the output file after a given size or a given time. Please note that tracks can only be split
right before a key frame. Therefore the split point may be a bit off from what the user has
specified.
At the moment mkvmerge(1) supports four different modes.
1. Splitting by size.
Syntax: --split [size:]d[k|m|g]
Examples: --split size:700m or --split 150000000
The parameter d may end with 'k', 'm' or 'g' to indicate that the size is in KB, MB or GB
respectively. Otherwise a size in bytes is assumed. After the current output file has reached
this size limit a new one will be started.
The 'size:' prefix may be omitted for compatibility reasons.
2. Splitting after a duration.
Syntax: --split [duration:]HH:MM:SS.nnnnnnnnn|ds
Examples: --split duration:00:60:00.000 or --split 3600s
The parameter must either have the form HH:MM:SS.nnnnnnnnn for specifying the duration in up to
nano-second precision or be a number d followed by the letter 's' for the duration in seconds.
HH is the number of hours, MM the number of minutes, SS the number of seconds and nnnnnnnnn the
number of nanoseconds. Both the number of hours and the number of nanoseconds can be omitted.
There can be up to nine digits after the decimal point. After the duration of the contents in the
current output has reached this limit a new output file will be started.
The 'duration:' prefix may be omitted for compatibility reasons.
3. Splitting after specific timestamps.
Syntax: --split timestamps:A[,B[,C...]]
Example: --split timestamps:00:45:00.000,01:20:00.250,6300s
The parameters A, B, C etc must all have the same format as the ones used for the duration (see
above). The list of timestamps is separated by commas. After the input stream has reached the
current split point's timestamp a new file is created. Then the next split point given in this
list is used.
The 'timestamps:' prefix must not be omitted.
4. Keeping specific parts by specifying timestamp ranges while discarding others.
Syntax: --split parts:start1-end1[,[+]start2-end2[,[+]start3-end3...]]
Examples:
1. --split parts:00:01:20-00:02:45,00:05:50-00:10:30
2. --split parts:00:01:20-00:02:45,+00:05:50-00:10:30
3. --split parts:-00:02:45,00:05:50-
The parts mode tells mkvmerge(1) to keep certain ranges of timestamps while discarding others.
The ranges to keep have to be listed after the parts: keyword and be separated by commas. A range
itself consists of a start and an end timestamp in the same format the other variations of
--split accept (e.g. both 00:01:20 and 80s refer to the same timestamp).
If a start timestamp is left out then it defaults to the previous range's end timestamp. If there
was no previous range then it defaults to the start of the file (see example 3).
If an end timestamp is left out then it defaults to the end of the source files which basically
tells mkvmerge(1) to keep the rest (see example 3).
Normally each range will be written to a new file. This can be changed so that consecutive ranges
are written to the same file. For that the user has to prefix the start timestamp with a +. This
tells mkvmerge(1) not to create a new file and instead append the range to the same file the
previous range was written to. Timestamps will be adjusted so that there will be no gap in the
output file even if there was a gap in the two ranges in the input file.
In example 1 mkvmerge(1) will create two files. The first will contain the content starting from
00:01:20 until 00:02:45. The second file will contain the content starting from 00:05:50 until
00:10:30.
In example 2 mkvmerge(1) will create only one file. This file will contain both the content
starting from 00:01:20 until 00:02:45 and the content starting from 00:05:50 until 00:10:30.
In example 3 mkvmerge(1) will create two files. The first will contain the content from the start
of the source files until 00:02:45. The second file will contain the content starting from
00:05:50 until the end of the source files.
Note
Note that mkvmerge(1) only makes decisions about splitting at key frame positions. This
applies to both the start and the end of each range. So even if an end timestamp is between
two key frames mkvmerge(1) will continue outputting the frames up to but excluding the
following key frame.
5. Keeping specific parts by specifying frame/field number ranges while discarding others.
Syntax: --split parts-frames:start1-end1[,[+]start2-end2[,[+]start3-end3...]]
Examples:
1. --split parts-frames:137-258,548-1211
2. --split parts-frames:733-912,+1592-2730
3. --split parts-frames:-430,2512-
The parts-frames mode tells mkvmerge(1) to keep certain ranges of frame/field numbers while
discarding others. The ranges to keep have to be listed after the parts-frames: keyword and be
separated by commas. A range itself consists of a start and an end frame/field number. Numbering
starts at 1.
If a start number is left out then it defaults to the previous range's end number. If there was
no previous range then it defaults to the start of the file (see example 3).
If an end number is left out then it defaults to the end of the source files which basically
tells mkvmerge(1) to keep the rest (see example 3).
Normally each range will be written to a new file. This can be changed so that consecutive ranges
are written to the same file. For that the user has to prefix the start number with a +. This
tells mkvmerge(1) not to create a new file and instead append the range to the same file the
previous range was written to. Timestamps will be adjusted so that there will be no gap in the
output file even if there was a gap in the two ranges in the input file.
Note
Note that mkvmerge(1) only makes decisions about splitting at key frame positions. This
applies to both the start and the end of each range. So even if an end frame/field number is
between two key frames mkvmerge(1) will continue outputting the frames up to but excluding
the following key frame.
In example 1 mkvmerge(1) will create two files. The first will contain the content starting from
the first key frame at or after 137 up to but excluding the first key frame at or after 258. The
second file will contain the content starting from 548 until 1211.
In example 2 mkvmerge(1) will create only one file. This file will contain both the content
starting from 733 until 912 and the content starting from 1592 until 2730.
In example 3 mkvmerge(1) will create two files. The first will contain the content from the start
of the source files until 430. The second file will contain the content starting from 2512 until
the end of the source files.
This mode considers only the first video track that is output. If no video track is output no
splitting will occur.
Note
The numbers given with this argument are interpreted based on the number of Matroska blocks
that are output. A single Matroska block contains either a full frame (for progressive
content) or a single field (for interlaced content). mkvmerge does not distinguish between
those two and simply counts the number of blocks. For example: If one wanted to split after
the 25th full frame with interlaced content one would have to use 50 (two fields per full
frame) as the split point.
6. Splitting after specific frames/fields.
Syntax: --split frames:A[,B[,C...]]
Example: --split frames:120,237,891
The parameters A, B, C etc must all be positive integers. Numbering starts at 1. The list of
frame/field numbers is separated by commas. After the input stream has reached the current split
point's frame/field number a new file is created. Then the next split point given in this list is
used.
The 'frames:' prefix must not be omitted.
This mode considers only the first video track that is output. If no video track is output no
splitting will occur.
Note
The numbers given with this argument are interpreted based on the number of Matroska blocks
that are output. A single Matroska block contains either a full frame (for progressive
content) or a single field (for interlaced content). mkvmerge does not distinguish between
those two and simply counts the number of blocks. For example: If one wanted to split after
the 25th full frame with interlaced content one would have to use 50 (two fields per full
frame) as the split point.
7. Splitting before specific chapters.
Syntax: --split chapters:all or --split chapters:A[,B[,C...]]
Example: --split chapters:5,8
The parameters A, B, C etc must all be positive integers. Numbering starts at 1. The list of
chapter numbers is separated by commas. Splitting will occur right before the first key frame
whose timestamp is equal to or bigger than the start timestamp for the chapters whose numbers are
listed. A chapter starting at 0s is never considered for splitting and discarded silently.
The keyword all can be used instead of listing all chapter numbers manually.
The 'chapters:' prefix must not be omitted.
Note
The Matroska file format supports arbitrary deeply nested chapter structures called 'edition
entries' and 'chapter atoms'. However, this mode only considers the top-most level of
chapters across all edition entries.
For this splitting mode the output filename is treated differently than for the normal operation. It
may contain a printf like expression '%d' including an optional field width, e.g. '%02d'. If it does
then the current file number will be formatted appropriately and inserted at that point in the
filename. If there is no such pattern then a pattern of '-%03d' is assumed right before the file's
extension: '-o output.mkv' would result in 'output-001.mkv' and so on. If there's no extension then
'-%03d' will be appended to the name.
--link
Link files to one another when splitting the output file. See the section on file linking below for
details.
--link-to-previous segment-UID
Links the first output file to the segment with the segment UID given by the segment-UID parameter.
See the section on file linking below for details.
If SID starts with = then its rest is interpreted as the name of a Matroska file whose segment UID is
read and used.
--link-to-next segment-UID
Links the last output file to the segment with the segment UID given by the segment-UID parameter.
See the section on file linking below for details.
If SID starts with = then its rest is interpreted as the name of a Matroska file whose segment UID is
read and used.
--append-mode mode
Determines how timestamps are calculated when appending files. The parameter mode can have two
values: 'file' which is also the default and 'track'.
When mkvmerge appends a track (called 'track2_1' from now on) from a second file (called 'file2') to
a track (called 'track1_1') from the first file (called 'file1') then it has to offset all timestamps
for 'track2_1' by an amount. For 'file' mode this amount is the highest timestamp encountered in
'file1' even if that timestamp was from a different track than 'track1_1'. In track mode the offset
is the highest timestamp of 'track1_1'.
Unfortunately mkvmerge cannot detect which mode to use reliably. Therefore it defaults to 'file'
mode. 'file' mode usually works better for files that have been created independently of each other;
e.g. when appending AVI or MP4 files. 'track' mode may work better for sources that are essentially
just parts of one big file, e.g. for VOB and EVO files.
Subtitle tracks are always treated as if 'file' mode were active even if 'track' mode actually is.
--append-to SFID1:STID1:DFID1:DTID1[,...]
This option controls to which track another track is appended. Each spec contains four IDs: a file
ID, a track ID, a second file ID and a second track ID. The first pair, "source file ID" and "source
track ID", identifies the track that is to be appended. The second pair, "destination file ID" and
"destination track ID", identifies the track the first one is appended to.
If this option has been omitted then a standard mapping is used. This standard mapping appends each
track from the current file to a track from the previous file with the same track ID. This allows for
easy appending if a movie has been split into two parts and both file have the same number of tracks
and track IDs with the command mkvmerge -o output.mkv part1.mkv +part2.mkv.
+
A single '+' causes the next file to be appended instead of added. The '+' can also be put in front
of the next file name. Therefore the following two commands are equivalent:
$ mkvmerge -o full.mkv file1.mkv + file2.mkv
$ mkvmerge -o full.mkv file1.mkv +file2.mkv
[ file1 file2 ]
If multiple file names are contained in a pair of square brackets then the second and all following
files will be appended to the first file named within the brackets.
This is an alternative syntax to using '+' between the file names. Therefore the following two
commands are equivalent:
$ mkvmerge -o full.mkv file1.mkv + file2.mkv
$ mkvmerge -o full.mkv '[' file1.mkv file2.mkv ']'
=
Normally mkvmerge(1) looks for files in the same directory as an input file that have the same base
name and only differ in their running number (e.g. 'VTS_01_1.VOB', 'VTS_01_2.VOB', 'VTS_01_3.VOB'
etc) and treats all of those files as if they were concatenated into a single big file. This option,
a single '=', causes mkvmerge not to look for those additional files.
The '=' can also be put in front of the next file name. Therefore the following two commands are
equivalent:
$ mkvmerge -o full.mkv = file1.mkv
$ mkvmerge -o full.mkv =file1.mkv
( file1 file2 )
If multiple file names are contained in a pair of parenthesis then those files will be treated as if
they were concatenated into a single big file consisting of the content of each of the files one
after the other.
This can be used for e.g. VOB files coming from a DVD or MPEG transport streams. It cannot be used if
each file contains its own set of headers which is usually the case with stand-alone files like AVI
or MP4.
Putting a file name into parenthesis also prevents mkvmerge(1) from looking for additional files with
the same base name as described in option =. Therefore these two command lines are equivalent:
$ mkvmerge -o out.mkv = file.mkv
$ mkvmerge -o out.mkv '(' file.mkv ')'
Several things should be noted:
1. There must be spaces both after the opening and before the closing parenthesis.
2. Every parameter between parenthesis is interpreted as a file name. Therefore all options applying
to this logical file must be listed before the opening parenthesis.
3. Some shells treat parenthesis as special characters. Hence you must escape or quote them as shown
in the example above.
Attachment support (more global options)
--attachment-description description
Plain text description of the following attachment. Applies to the next --attach-file or
--attach-file-once option.
--attachment-mime-type MIME type
MIME type of the following attachment. Applies to the next --attach-file or --attach-file-once
option. A list of officially recognized MIME types can be found e.g. at the IANA homepage[2]. The
MIME type is mandatory for an attachment.
--attachment-name name
Sets the name that will be stored in the output file for this attachment. If this option is not given
then the name will be derived from the file name of the attachment as given with the --attach-file or
the --attach-file-once option.
--attach-file file-name, --attach-file-once file-name
Creates a file attachment inside the Matroska file. The MIME type must have been set before this
option can used. The difference between the two forms is that during splitting the files attached
with --attach-file are attached to all output files while the ones attached with --attach-file-once
are only attached to the first file created. If splitting is not used then both do the same.
mkvextract(1) can be used to extract attached files from a Matroska file.
Options that can be used for each input file
-a, --audio-tracks [!]n,m,...
Copy the audio tracks n, m etc. The numbers are track IDs which can be obtained with the --identify
switch. They're not simply the track numbers (see section track IDs). Default: copy all audio tracks.
Instead of track IDs you can also provide ISO 639-2 language codes. This will only work for source
files that provide language tags for their tracks.
Default: copy all tracks of this kind.
If the IDs are prefixed with ! then the meaning is reversed: copy all tracks of this kind but the
ones listed after the !.
-d, --video-tracks [!]n,m,...
Copy the video tracks n, m etc. The numbers are track IDs which can be obtained with the --identify
switch. They're not simply the track numbers (see section track IDs). Default: copy all video tracks.
Instead of track IDs you can also provide ISO 639-2 language codes. This will only work for source
files that provide language tags for their tracks.
If the IDs are prefixed with ! then the meaning is reversed: copy all tracks of this kind but the
ones listed after the !.
-s, --subtitle-tracks [!]n,m,...
Copy the subtitle tracks n, m etc. The numbers are track IDs which can be obtained with the
--identify switch. They're not simply the track numbers (see section track IDs). Default: copy all
subtitle tracks.
Instead of track IDs you can also provide ISO 639-2 language codes. This will only work for source
files that provide language tags for their tracks.
If the IDs are prefixed with ! then the meaning is reversed: copy all tracks of this kind but the
ones listed after the !.
-b, --button-tracks [!]n,m,...
Copy the button tracks n, m etc. The numbers are track IDs which can be obtained with the --identify
switch. They're not simply the track numbers (see section track IDs). Default: copy all button
tracks.
Instead of track IDs you can also provide ISO 639-2 language codes. This will only work for source
files that provide language tags for their tracks.
If the IDs are prefixed with ! then the meaning is reversed: copy all tracks of this kind but the
ones listed after the !.
--track-tags [!]n,m,...
Copy the tags for tracks n, m etc. The numbers are track IDs which can be obtained with the
--identify switch (see section track IDs). They're not simply the track numbers. Default: copy tags
for all tracks.
If the IDs are prefixed with ! then the meaning is reversed: copy everything but the IDs listed
after the !.
-m, --attachments [!]n[:all|first],m[:all|first],...
Copy the attachments with the IDs n, m etc to all or only the first output file. Each ID can be
followed by either ':all' (which is the default if neither is entered) or ':first'. If splitting is
active then those attachments whose IDs are specified with ':all' are copied to all of the resulting
output files while the others are only copied into the first output file. If splitting is not active
then both variants have the same effect.
The default is to copy all attachments to all output files.
If the IDs are prefixed with ! then the meaning is reversed: copy everything but the IDs listed
after the !.
-A, --no-audio
Don't copy any audio track from this file.
-D, --no-video
Don't copy any video track from this file.
-S, --no-subtitles
Don't copy any subtitle track from this file.
-B, --no-buttons
Don't copy any button track from this file.
-T, --no-track-tags
Don't copy any track specific tags from this file.
--no-chapters
Don't copy chapters from this file.
-M, --no-attachments
Don't copy attachments from this file.
--no-global-tags
Don't copy global tags from this file.
--chapter-charset character-set
Sets the charset that is used for the conversion to UTF-8 for chapter information contained in the
source file. See the section about text files and character sets for an explanation how mkvmerge(1)
converts between character sets.
--chapter-language language-code
Sets the ISO 639-2 language code that is written for each chapter entry. This option can be used for
source files that contain chapters but no information about the chapters' languages, e.g. for MP4 and
OGM files.
-y, --sync TID:d[,o[/p]]
Adjust the timestamps of the track with the id TID by d ms. The track IDs are the same as the ones
given with --identify (see section track IDs).
o/p: adjust the timestamps by o/p to fix linear drifts. p defaults to 1 if omitted. Both o and p can
be floating point numbers.
Defaults: no manual sync correction (which is the same as d = 0 and o/p = 1.0).
This option can be used multiple times for an input file applying to several tracks by selecting
different track IDs each time.
--cues TID:none|iframes|all
Controls for which tracks cue (index) entries are created for the given track (see section track
IDs). 'none' inhibits the creation of cue entries. For 'iframes' only blocks with no backward or
forward references ( = I frames in video tracks) are put into the cue sheet. 'all' causes mkvmerge(1)
to create cue entries for all blocks which will make the file very big.
The default is 'iframes' for video and subtitle tracks and 'none' for audio tracks. See also option
--no-cues which inhibits the creation of cue entries regardless of the --cues options used.
This option can be used multiple times for an input file applying to several tracks by selecting
different track IDs each time.
--default-track TID[:bool]
Sets the 'default' flag for the given track (see section track IDs) if the optional argument bool is
not present. If the user does not explicitly select a track himself then the player should prefer the
track that has his 'default' flag set. Only one track of each kind (audio, video, subtitles, buttons)
can have his 'default' flag set. If the user wants no track to have the default track flag set then
he has to set bool to 0 for all tracks.
This option can be used multiple times for an input file applying to several tracks by selecting
different track IDs each time.
--forced-track TID[:bool]
Sets the 'forced' flag for the given track (see section track IDs) if the optional argument bool is
not present. A player must play all tracks for which this flag is set to 1.
This option can be used multiple times for an input file applying to several tracks by selecting
different track IDs each time.
--blockadd TID:level
Keep only the BlockAdditions up to the level level for the given track. The default is to keep all
levels. This option only affects certain kinds of codecs like WAVPACK4.
--track-name TID:name
Sets the track name for the given track (see section track IDs) to name.
--language TID:language
Sets the language for the given track (see section track IDs). Both ISO 639-2 language codes and ISO
639-1 country codes are allowed. The country codes will be converted to language codes automatically.
All languages including their ISO 639-2 codes can be listed with the --list-languages option.
This option can be used multiple times for an input file applying to several tracks by selecting
different track IDs each time.
-t, --tags TID:file-name
Read tags for the track with the number TID from the file file-name. See the section about tags below
for details.
--aac-is-sbr TID[:0|1]
Tells mkvmerge(1) that the track with the ID TID is SBR AAC (also known as HE-AAC or AAC+). This
options is needed if a) the source file is an AAC file (not for a Matroska file) and b) the AAC file
contains SBR AAC data. The reason for this switch is that it is technically impossible to
automatically tell normal AAC data from SBR AAC data without decoding a complete AAC frame. As there
are several patent issues with AAC decoders mkvmerge(1) will never contain this decoding stage. So
for SBR AAC files this switch is mandatory. The resulting file might not play back correctly or even
not at all if the switch was omitted.
If the source file is a Matroska file then the CodecID should be enough to detect SBR AAC. However,
if the CodecID is wrong then this switch can be used to correct that.
If mkvmerge wrongfully detects that an AAC file is SBR then you can add ':0' to the track ID.
--reduce-to-core TID
Some audio codecs have a lossy core and optional extensions that implement lossless decoding. This
option tells mkvmerge(1) to only copy the core but not the extensions. By default mkvmerge(1) copies
both the core and the extensions.
Currently only DTS tracks are affected by this option. TrueHD tracks that contain an embedded AC-3
core are instead presented as two separate tracks for which the user can select which track to copy.
For DTS such a scheme would not work as the HD extensions cannot be decoded by themselves – unlike
the TrueHD data.
--remove-dialog-normalization-gain TID
Some audio codecs contain header fields that tell the decoder or player to apply a (usually negative)
gain for dialog normalization. This option tells mkvmerge(1) to remove or minimize that gain by
modifying the corresponding header fields.
Currently only AC-3, DTS and TrueHD tracks are affected by this option.
--timestamps TID:file-name
Read the timestamps to be used for the specific track ID from file-name. These timestamps forcefully
override the timestamps that mkvmerge(1) normally calculates. Read the section about external
timestamp files.
--default-duration TID:x
Forces the default duration of a given track to the specified value. Also modifies the track's
timestamps to match the default duration. The argument x must be postfixed with 's', 'ms', 'us',
'ns', 'fps', 'p' or 'i' to specify the default duration in seconds, milliseconds, microseconds,
nanoseconds, 'frames per second', 'progressive frames per second' or 'interlaced frames per second'
respectively. The number x itself can be a floating point number or a fraction.
If the default duration is not forced then mkvmerge will try to derive the track's default duration
from the container and/or the encoded bitstream for certain track types, e.g. AVC/H.264 or MPEG-2.
This option can also be used to change the FPS of video tracks without having to use an external
timestamp file.
--fix-bitstream-timing-information TID[:0|1]
Normally mkvmerge(1) does not change the timing information (frame/field rate) stored in the video
bitstream. With this option that information is adjusted to match the container timing information.
The container timing information can come from various sources: from the command line (see option
--default-duration), the source container or derived from the bitstream.
Note
This has only been implemented for AVC/H.264 video tracks so far.
--nalu-size-length TID:n
Forces the NALU size length to n bytes. This parameter is only used if the AVC/H.264 elementary
stream packetizer is used. If left out it defaults to 4 bytes, but there are files that contain
frames or slices that are all smaller than 65536 bytes. For such files you can use this parameter and
decrease the size to 2.
--compression TID:n
Selects the compression method to be used for the track. Note that the player also has to support
this method. Valid values are 'none', 'zlib' and 'mpeg4_p2'/'mpeg4p2'.
The compression method 'mpeg4_p2'/'mpeg4p2' is a special compression method called 'header removal'
that is only available for MPEG4 part 2 video tracks.
The default for some subtitle types is 'zlib' compression. This compression method is also the one
that most if not all playback applications support. Support for other compression methods other than
'none' is not assured.
Options that only apply to video tracks
-f, --fourcc TID:FourCC
Forces the FourCC to the specified value. Works only for video tracks in the 'MS compatibility mode'.
--display-dimensions TID:widthxheight
Matroska files contain two values that set the display properties that a player should scale the
image on playback to: display width and display height. These values can be set with this option,
e.g. '1:640x480'.
Another way to specify the values is to use the --aspect-ratio or the --aspect-ratio-factor option
(see below). These options are mutually exclusive.
--aspect-ratio TID:ratio|width/height
Matroska files contain two values that set the display properties that a player should scale the
image on playback to: display width and display height. With this option mkvmerge(1) will
automatically calculate the display width and display height based on the image's original width and
height and the aspect ratio given with this option. The ratio can be given either as a floating point
number ratio or as a fraction 'width/height', e.g. '16/9'.
Another way to specify the values is to use the --aspect-ratio-factor or --display-dimensions options
(see above and below). These options are mutually exclusive.
--aspect-ratio-factor TID:factor|n/d
Another way to set the aspect ratio is to specify a factor. The original aspect ratio is first
multiplied with this factor and used as the target aspect ratio afterwards.
Another way to specify the values is to use the --aspect-ratio or --display-dimensions options (see
above). These options are mutually exclusive.
--cropping TID:left,top,right,bottom
Sets the pixel cropping parameters of a video track to the given values.
--colour-matrix TID:n
Sets the matrix coefficients of the video used to derive luma and chroma values from red, green and
blue color primaries. The parameter n is an integer rangeing from 0 and 10.
Valid values and their meaning are:
0: GBR, 1: BT709, 2: unspecified, 3: reserved, 4: FCC, 5: BT470BG, 6: SMPTE 170M, 7: SMPTE 240M, 8:
YCOCG, 9: BT2020 non-constant luminance, 10: BT2020 constant luminance
--colour-bits-per-channel TID:n
Sets the number of coded bits for a colour channel. A value of 0 indicates that the number of bits is
unspecified.
--chroma-subsample TID:hori,vert
The amount of pixels to remove in the Cr and Cb channels for every pixel not removed
horizontally/vertically.
Example: For video with 4:2:0 chroma subsampling, the parameter should be set to TID:1,1.
--cb-subsample TID:hori,vert
The amount of pixels to remove in the Cb channel for every pixel not removed horizontally/vertically.
This is additive with --chroma-subsample.
Example: For video with 4:2:1 chroma subsampling, the parameter --chroma-subsample should be set to
TID:1,0 and Cb-subsample should be set to TID:1,0.
--chroma-siting TID:hori,vert
Sets how chroma is sited horizontally/vertically (0: unspecified, 1: top collocated, 2: half).
--colour-range TID:n
Sets the clipping of the color ranges (0: unspecified, 1: broadcast range, 2: full range (no
clipping), 3: defined by MatrixCoefficients/TransferCharacteristics).
--colour-transfer-characteristics TID:n
The transfer characteristics of the video.
Valid values and their meaning are:
0: reserved, 1: ITU-R BT.709, 2: unspecified, 3: reserved, 4: gamma 2.2 curve, 5: gamma 2.8 curve, 6:
SMPTE 170M, 7: SMPTE 240M, 8: linear, 9: log, 10: log sqrt, 11: IEC 61966-2-4, 12: ITU-R BT.1361
extended colour gamut, 13: IEC 61966-2-1, 14: ITU-R BT.2020 10 bit, 15: ITU-R BT.2020 12 bit, 16:
SMPTE ST 2084, 17: SMPTE ST 428-1; 18: ARIB STD-B67 (HLG)
--colour-primaries TID:n
Sets the colour primaries of the video.
Valid values and their meaning are:
0: reserved, 1: ITU-R BT.709, 2: unspecified, 3: reserved, 4: ITU-R BT.470M, 5: ITU-R BT.470BG, 6:
SMPTE 170M, 7: SMPTE 240M, 8: FILM, 9: ITU-R BT.2020, 10: SMPTE ST 428-1, 22: JEDEC P22 phosphors
--max-content-light TID:n
Sets the maximum brightness of a single pixel (Maximum Content Light Level) in candelas per square
meter (cd/m²). The value of n should be a non-negtive integer.
--max-frame-light TID:n
Sets the maximum brightness of a single full frame (Maximum Frame-Average Light Level) in candelas
per square meter (cd/m²). The value of n should be a non-negtive integer.
--chromaticity-coordinates TID:red-x,red-y,green-x,green-y,blue-x,blue-y
Sets the red/green/blue chromaticity coordinates as defined by CIE 1931.
--white-colour-coordinates TID:x,y
Sets the white colour chromaticity coordinates as defined by CIE 1931.
--max-luminance TID:float
Sets the maximum luminance in candelas per square meter (cd/m²). The value should be less than
9999.99.
--min-luminance TID:float
Sets the minimum luminance in candelas per square meter (cd/m²). The value should be less than
999.9999.
--projection-type TID:method
Sets the video projection method used. Valid values are 0 (rectangular projection), 1
(equirectangular projection), 2 (cubemap projection) and 3 (mesh projection).
--projection-private TID:data
Sets private data that only applies to a specific projection. Data must be given as hex numbers with
or without the "0x" prefix, with or without spaces.
--projection-pose-yaw TID:float
Specifies a yaw rotation to the projection.
--projection-pose-pitch TID:float
Specifies a pitch rotation to the projection.
--projection-pose-roll TID:float
Specifies a roll rotation to the projection.
--field-order TID:n
Sets the field order for the video track with the track ID TID. The order must be one of the
following numbers:
0: progressive; 1: interlaced with top field displayed first and top field stored first; 2:
undetermined field order; 6: interlaced with bottom field displayed first and bottom field stored
first; 9: interlaced with bottom field displayed first and top field stored first; 14: interlaced
with top field displayed first and bottom field stored first
--stereo-mode TID:n|keyword
Sets the stereo mode for the video track with the track ID TID. The mode can either be a number n
between 0 and 14 or one of these keywords:
'mono', 'side_by_side_left_first', 'top_bottom_right_first', 'top_bottom_left_first',
'checkerboard_right_first', 'checkerboard_left_first', 'row_interleaved_right_first',
'row_interleaved_left_first', 'column_interleaved_right_first', 'column_interleaved_left_first',
'anaglyph_cyan_red', 'side_by_side_right_first', 'anaglyph_green_magenta',
'both_eyes_laced_left_first', 'both_eyes_laced_right_first'.
Options that only apply to text subtitle tracks
--sub-charset TID:character-set
Sets the character set for the conversion to UTF-8 for UTF-8 subtitles for the given track ID. If not
specified the charset will be derived from the current locale settings. Note that a charset is not
needed for subtitles read from Matroska files or from Kate streams, as these are always stored in
UTF-8. See the section about text files and character sets for an explanation how mkvmerge(1)
converts between character sets.
This option can be used multiple times for an input file applying to several tracks by selecting
different track IDs each time.
Other options
-i, --identify file-name
Will let mkvmerge(1) probe the single file and report its type, the tracks contained in the file and
their track IDs. If this option is used then the only other option allowed is the filename.
The output format used for the result can be changed with the option --identification-format.
-J file-name
This is a convenient alias for "--identification-format json --identify file-name".
-F, --identification-format format
Determines the output format used by the --identify option. The following formats are supported: text
(the default if this option isn't used) and json.
1. The text format is short and human-readable. It consists of one line per item found (container,
tracks, attachments etc.).
This format is not meant to be parsed. The output will be translated into the language
mkvmerge(1) uses (see also --ui-language).
2. The json format outputs a machine-readable JSON representation. This format follows the JSON
schema described in the following file:
mkvmerge-identification-output-schema-v12.json[3]
All versions of the JSON schema are available both online and in the released source code
archives.
--probe-range-percentage percentage
File types such as MPEG program and transport streams (.vob, .m2ts) require parsing a certain amount
of data in order to detect all tracks contained in the file. This amount is 0.3% of the source file's
size or 10 MB, whichever is higher.
If tracks are known to be present but not found then the percentage to probe can be changed with this
option. The minimum of 10 MB is built-in and cannot be changed.
-l, --list-types
Lists supported input file types.
--list-languages
Lists all languages and their ISO 639-2 code which can be used with the --language option.
--priority priority
Sets the process priority that mkvmerge(1) runs with. Valid values are 'lowest', 'lower', 'normal',
'higher' and 'highest'. If nothing is given then 'normal' is used. On Unix like systems mkvmerge(1)
will use the nice(2) function. Therefore only the super user can use 'higher' and 'highest'. On
Windows all values are useable for every user.
Selecting 'lowest' also causes mkvmerge(1) to select idle I/O priority in addition to the lowest
possible process priority.
--command-line-charset character-set
Sets the character set to convert strings given on the command line from. It defaults to the
character set given by system's current locale. This settings applies to arguments of the following
options: --title, --track-name and --attachment-description.
--output-charset character-set
Sets the character set to which strings are converted that are to be output. It defaults to the
character set given by system's current locale.
-r, --redirect-output file-name
Writes all messages to the file file-name instead of to the console. While this can be done easily
with output redirection there are cases in which this option is needed: when the terminal
reinterprets the output before writing it to a file. The character set set with --output-charset is
honored.
--flush-on-close
Tells the program to flush all data cached in memory to storage when closing files opened for
writing. This can be used to prevent data loss on power outages or to circumvent certain problems in
the operating system or drivers. The downside is that multiplexing will take longer as mkvmerge will
wait until all data has been written to the storage before exiting. See issues #2469 and #2480 on the
MKVToolNix bug tracker for in-depth discussions on the pros and cons.
--ui-language code
Forces the translations for the language code to be used (e.g. 'de_DE' for the German translations).
Entering 'list' as the code will cause the program to output a list of available translations.
--abort-on-warnings
Tells the program to abort after the first warning is emitted. The program's exit code will be 1.
--deterministic seed
Enables the creation of byte-identical files if the same version of mkvmerge(1) is used with the same
source files, the same set of options and the same seed. Note that the "date" segment information
field is not written in this mode.
The seed can be an arbitrary string and does not have to be a number.
The result of byte-identical files is only guaranteed under the following conditions:
1. The same version of mkvmerge(1) built with the same versions of libEBML and libMatroska is used.
2. The source files used are byte-identical.
3. The same command line options are used in the same order (with the notable exception of --output
...).
Using other versions of mkvmerge(1) or other command-line options may result in the same
byte-identical file but is not guaranteed to do so.
--debug topic
Turn on debugging for a specific feature. This option is only useful for developers.
--engage feature
Turn on experimental features. A list of available features can be requested with mkvmerge --engage
list. These features are not meant to be used in normal situations.
--gui-mode
Turns on GUI mode. In this mode specially-formatted lines may be output that can tell a controlling
GUI what's happening. These messages follow the format '#GUI#message'. The message may be followed by
key/value pairs as in '#GUI#message#key1=value1#key2=value2...'. Neither the messages nor the keys
are ever translated and always output in English.
@options-file.json
Reads additional command line arguments from the file options-file. See the section about option
files for further information.
--capabilities
Lists information about optional features that have been compiled in and exit. The first line output
will be the version information. All following lines contain exactly one word whose presence
indicates that the feature has been compiled in. These features are:
• 'FLAC' -- reading raw FLAC files and handling FLAC tracks in other containers, e.g. Ogg or
Matroska.
-h, --help
Show usage information and exit.
-V, --version
Show version information and exit.
USAGE
For each file the user can select which tracks mkvmerge(1) should take. They are all put into the file
specified with -o. A list of known (and supported) source formats can be obtained with the -l option.
Important
The order of command line options is important. Please read the section "Option order" if you're new
to the program.
OPTION ORDER
The order in which options are entered is important for some options. Options fall into two categories:
1. Options that affect the whole program and are not tied to any input file. These include but are not
limited to --command-line-charset, --output or --title. These can appear anywhere on the command
line.
2. Options that affect a single input file or a single track in an input file. These options all apply
to the following input file on the command line. All options applying to the same input (or to tracks
from the same input file) file can be written in any order as long as they all appear before that
input file's name. Examples for options applying to an input file are --no-chapters or
--chapter-charset. Examples for options applying to a single track are --default-duration or
--language.
The options are processed from left to right. If an option appears multiple times within the same scope
then the last occurrence will be used. Therefore the title will be set to "Something else" in the
following example:
$ mkvmerge -o output.mkv --title 'This and that' input.avi --title 'Something else'
The following example shows that using the --language option twice is OK because they're used in
different scopes. Even though they apply to the same track ID they apply to different input files and
therefore have different scopes:
$ mkvmerge -o output.mkv --language 0:fre français.ogg --language 0:deu deutsch.ogg
EXAMPLES
Let's assume you have a file called MyMovie.avi and the audio track in a separate file, e.g.
'MyMovie.wav'. First you want to encode the audio to OggVorbis:
$ oggenc -q4 -oMyMovie.ogg MyMovie.wav
After a couple of minutes you can join video and audio:
$ mkvmerge -o MyMovie-with-sound.mkv MyMovie.avi MyMovie.ogg
If your AVI already contains an audio track then it will be copied as well (if mkvmerge(1) supports the
audio format). To avoid that simply do
$ mkvmerge -o MyMovie-with-sound.mkv -A MyMovie.avi MyMovie.ogg
After some minutes of consideration you rip another audio track, e.g. the director's comments or another
language to 'MyMovie-add-audio.wav'. Encode it again and join it up with the other file:
$ oggenc -q4 -oMyMovie-add-audio.ogg MyMovie-add-audio.wav
$ mkvmerge -o MM-complete.mkv MyMovie-with-sound.mkv MyMovie-add-audio.ogg
The same result can be achieved with
$ mkvmerge -o MM-complete.mkv -A MyMovie.avi MyMovie.ogg MyMovie-add-audio.ogg
Now fire up mplayer and enjoy. If you have multiple audio tracks (or even video tracks) then you can tell
mplayer which track to play with the '-vid' and '-aid' options. These are 0-based and do not distinguish
between video and audio.
If you need an audio track synchronized you can do that easily. First find out which track ID the Vorbis
track has with
$ mkvmerge --identify outofsync.ogg
Now you can use that ID in the following command line:
$ mkvmerge -o goodsync.mkv -A source.avi -y 12345:200 outofsync.ogg
This would add 200ms of silence at the beginning of the audio track with the ID 12345 taken from
'outofsync.ogg'.
Some movies start synced correctly but slowly drift out of sync. For these kind of movies you can specify
a delay factor that is applied to all timestamps -- no data is added or removed. So if you make that
factor too big or too small you'll get bad results. An example is that an episode I transcoded was 0.2
seconds out of sync at the end of the movie which was 77340 frames long. At 29.97fps 0.2 seconds
correspond to approx. 6 frames. So I did
$ mkvmerge -o goodsync.mkv -y 23456:0,77346/77340 outofsync.mkv
The result was fine.
The sync options can also be used for subtitles in the same manner.
For text subtitles you can either use some Windows software (like SubRipper) or the subrip package found
in transcode(1)'s sources in the 'contrib/subrip' directory. The general process is:
1. extract a raw subtitle stream from the source:
$ tccat -i /path/to/copied/dvd/ -T 1 -L | tcextract -x ps1 -t vob -a 0x20 | subtitle2pgm -o mymovie
2. convert the resulting PGM images to text with gocr:
$ pgm2txt mymovie
3. spell-check the resulting text files:
$ ispell -d american *txt
4. convert the text files to a SRT file:
$ srttool -s -w -i mymovie.srtx -o mymovie.srt
The resulting file can be used as another input file for mkvmerge(1):
$ mkvmerge -o mymovie.mkv mymovie.avi mymovie.srt
If you want to specify the language for a given track then this is easily done. First find out the ISO
639-2 code for your language. mkvmerge(1) can list all of those codes for you:
$ mkvmerge --list-languages
Search the list for the languages you need. Let's assume you have put two audio tracks into a Matroska
file and want to set their language codes and that their track IDs are 2 and 3. This can be done with
$ mkvmerge -o with-lang-codes.mkv --language 2:ger --language 3:dut without-lang-codes.mkv
As you can see you can use the --language switch multiple times.
Maybe you'd also like to have the player use the Dutch language as the default language. You also have
extra subtitles, e.g. in English and French, and want to have the player display the French ones by
default. This can be done with
$ mkvmerge -o with-lang-codes.mkv --language 2:ger --language 3:dut --default-track 3 without-lang-codes.mkv --language 0:eng english.srt --default-track 0 --language 0:fre french.srt
If you do not see the language or default track flags that you've specified in mkvinfo(1)'s output then
please read the section about default values.
Turn off the compression for an input file.
$ mkvmerge -o no-compression.mkv --compression -1:none MyMovie.avi --compression -1:none mymovie.srt
TRACK IDS
Regular track IDs
Some of the options for mkvmerge(1) need a track ID to specify which track they should be applied to.
Those track IDs are printed by the readers when demuxing the current input file, or if mkvmerge(1) is
called with the --identify option. An example for such output:
$ mkvmerge -i v.mkv
File 'v.mkv': container: Matroska
Track ID 0: video (V_MS/VFW/FOURCC, DIV3)
Track ID 1: audio (A_MPEG/L3)
Do not confuse the track IDs that are assigned to the tracks that are placed in the output MKV file with
the track IDs of the input files. Only the input file track IDs are used for options needing these
values.
Also note that each input file has its own set of track IDs. Therefore the track IDs for file 'file1.ext'
as reported by 'mkvmerge --identify' do not change no matter how many other input files are there or in
which position 'file1.ext' is used.
Track IDs are assigned like this:
• AVI files: The video track has the ID 0. The audio tracks get IDs in ascending order starting at 1.
• AAC, AC-3, MP3, SRT and WAV files: The one 'track' in that file gets the ID 0.
• Most other files: The track IDs are assigned in order the tracks are found in the file starting at 0.
The options that use the track IDs are the ones whose description contains 'TID'. The following options
use track IDs as well: --audio-tracks, --video-tracks, --subtitle-tracks, --button-tracks and
--track-tags.
Special track IDs
There are several IDs that have special meaning and do not occur in the identification output.
The special track ID '-1' is a wild card and applies the given switch to all tracks that are read from an
input file.
The special track ID '-2' refers to the chapters in a source file. Currently only the --sync option uses
this special ID. As an alternative to --sync -2:... the option --chapter-sync ... can be used.
TEXT FILES AND CHARACTER SET CONVERSIONS
Note
This section applies to all programs in MKVToolNix even if it only mentions mkvmerge(1).
Introduction
All text in a Matroska file is encoded in UTF-8. This means that mkvmerge(1) has to convert every text
file it reads as well as every text given on the command line from one character set into UTF-8. In
return this also means that mkvmerge(1)'s output has to be converted back to that character set from
UTF-8, e.g. if a non-English translation is used with --ui-language or for text originating from a
Matroska file.
mkvmerge(1) does this conversion automatically based on the presence of a byte order marker (short: BOM)
or the system's current locale. How the character set is inferred from the locale depends on the
operating system that mkvmerge(1) is run on.
Byte order markers (BOM)
Text files that start with a BOM are already encoded in one representation of UTF. mkvmerge(1) supports
the following five modes: UTF-8, UTF-16 Little and Big Endian, UTF-32 Little and Big Endian. Text files
with a BOM are automatically converted to UTF-8. Any of the parameters that would otherwise set the
character set for such a file (e.g. --sub-charset) is silently ignored.
Linux and Unix-like systems including macOS
On Unix-like systems mkvmerge(1) uses the setlocale(3) system call which in turn uses the environment
variables LANG, LC_ALL and LC_CYPE. The resulting character set is often one of UTF-8 or the ISO-8859-*
family and is used for all text file operations and for encoding strings on the command line and for
output to the console.
Windows
On Windows the default character set used for converting text files is determined by a call to the
GetACP() system call.
Reading the command line is done with the GetCommandLineW() function which already returns a Unicode
string. Therefore the option --command-line-charset is ignored on Windows.
Output to the console consists of three scenarios:
1. If the output is redirected with the option --redirect-output then the default charset is UTF-8. This
can be changed with --output-charset.
If the output is redirected with cmd.exe itself, e.g. with mkvinfo file.mkv > info.txt, then the
charset is always UTF-8 and cannot be changed.
Otherwise (when writing directly to the console) the Windows function WriteConsoleW() is used and the
option --output-charset is ignored. The console should be able to output all Unicode characters for
which the corresponding language support is installed (e.g. Chinese characters might not be displayed
on English Windows versions).
Command line options
The following options exist that allow specifying the character sets:
• --sub-charset for text subtitle files and for text subtitle tracks stored in container formats for
which the character set cannot be determined unambiguously (e.g. Ogg files),
• --chapter-charset for chapter text files and for chapters and file titles stored in container formats
for which the character set cannot be determined unambiguously (e.g. Ogg files for chapter
information, track and file titles etc; MP4 files for chapter information),
• --command-line-charset for all strings on the command line,
• --output-charset for all strings written to the console or to a file if the output has been
redirected with the --redirect-output option. On non-Windows systems the default for the output
charset is the system's current charset. On Windows it defaults to UTF-8 both for redirecting with
--redirect-output and with cmd.exe itself, e.g. mkvinfo file.mkv > info.txt.
OPTION FILES
An option file is a file mkvmerge(1) can read additional command line arguments from. This can be used in
order to circumvent certain limitations of the shell or the operating system when executing external
programs like a limited command line length.
An option file contains JSON-formatted data. Its content must be a valid JSON array consisting solely of
JSON strings. The file's encoding must be UTF-8. The file should not start with a byte order marker
(BOM), but if one exists, it will be skipped.
The rules for escaping special characters inside JSON are the ones in the official JSON specification,
RFC 7159[4].
The command line 'mkvmerge -o "my file.mkv" -A "a movie.avi" sound.ogg' could be converted into the
following JSON option file called e.g. 'options.json':
[
"-o",
"c:\\Matroska\\my file.mkv",
"--title",
"#65",
"-A",
"a movie.avi",
"sound.ogg"
]
SUBTITLES
There are several text and bitmap subtitle formats that can be embedded into Matroska. Text subtitles
must be recoded to UTF-8 so that they can be displayed correctly by a player (see the section about text
files and character sets for an explanation how mkvmerge(1) converts between character sets). Kate
subtitles are already encoded in UTF-8 and do not have to be re-encoded.
The following subtitle formats are supported at the moment:
• Subtitle Ripper (SRT) files
• Substation Alpha (SSA) / Advanced Substation Alpha scripts (ASS)
• Universal Subtitle Format (USF) files
• OggKate streams
• VobSub bitmap subtitle files
• PGS bitmap subtitle files as found on BluRay discs
FILE LINKING
Matroska supports file linking which simply says that a specific file is the predecessor or successor of
the current file. To be precise, it's not really the files that are linked but the Matroska segments. As
most files will probably only contain one Matroska segment the following explanations use the term 'file
linking' although 'segment linking' would be more appropriate.
Each segment is identified by a unique 128 bit wide segment UID. This UID is automatically generated by
mkvmerge(1). The linking is done primarily via putting the segment UIDs (short: SID) of the previous/next
file into the segment header information. mkvinfo(1) prints these SIDs if it finds them.
If a file is split into several smaller ones and linking is used then the timestamps will not start at 0
again but will continue where the last file has left off. This way the absolute time is kept even if the
previous files are not available (e.g. when streaming). If no linking is used then the timestamps should
start at 0 for each file. By default mkvmerge(1) does not use file linking. If you want that you can turn
it on with the --link option. This option is only useful if splitting is activated as well.
Regardless of whether splitting is active or not the user can tell mkvmerge(1) to link the produced files
to specific SIDs. This is achieved with the options --link-to-previous and --link-to-next. These options
accept a segment SID in the format that mkvinfo(1) outputs: 16 hexadecimal numbers between 0x00 and 0xff
prefixed with '0x' each, e.g. '0x41 0xda 0x73 0x66 0xd9 0xcf 0xb2 0x1e 0xae 0x78 0xeb 0xb4 0x5e 0xca 0xb3
0x93'. Alternatively a shorter form can be used: 16 hexadecimal numbers between 0x00 and 0xff without the
'0x' prefixes and without the spaces, e.g. '41da7366d9cfb21eae78ebb45ecab393'.
If splitting is used then the first file is linked to the SID given with --link-to-previous and the last
file is linked to the SID given with --link-to-next. If splitting is not used then the one output file
will be linked to both of the two SIDs.
DEFAULT VALUES
The Matroska specification states that some elements have a default value. Usually an element is not
written to the file if its value is equal to its default value in order to save space. The elements that
the user might miss in mkvinfo(1)'s output are the language and the default track flag elements. The
default value for the language is English ('eng'), and the default value for the default track flag is
true. Therefore if you used --language 0:eng for a track then it will not show up in mkvinfo(1)'s output.
ATTACHMENTS
Maybe you also want to keep some photos along with your Matroska file, or you're using SSA subtitles and
need a special TrueType font that's really rare. In these cases you can attach those files to the
Matroska file. They will not be just appended to the file but embedded in it. A player can then show
those files (the 'photos' case) or use them to render the subtitles (the 'TrueType fonts' case).
Here's an example how to attach a photo and a TrueType font to the output file:
$ mkvmerge -o output.mkv -A video.avi sound.ogg \
--attachment-description "Me and the band behind the stage in a small get-together" \
--attachment-mime-type image/jpeg \
--attach-file me_and_the_band.jpg \
--attachment-description "The real rare and unbelievably good looking font" \
--attachment-mime-type application/octet-stream \
--attach-file really_cool_font.ttf
If a Matroska containing attachments file is used as an input file then mkvmerge(1) will copy the
attachments into the new file. The selection which attachments are copied and which are not can be
changed with the options --attachments and --no-attachments.
CHAPTERS
The Matroska chapter system is more powerful than the old known system used by OGM files. The full
specifications can be found at the Matroska website[1].
mkvmerge(1) supports two kinds of chapter files as its input. The first format, called 'simple chapter
format', is the same format that the OGM tools expect. The second format is a XML based chapter format
which supports all of Matroska's chapter functionality.
The simple chapter format
This format consists of pairs of lines that start with 'CHAPTERxx=' and 'CHAPTERxxNAME=' respectively.
The first one contains the start timestamp while the second one contains the title. Here's an example:
CHAPTER01=00:00:00.000
CHAPTER01NAME=Intro
CHAPTER02=00:02:30.000
CHAPTER02NAME=Baby prepares to rock
CHAPTER03=00:02:42.300
CHAPTER03NAME=Baby rocks the house
mkvmerge(1) will transform every pair or lines into one Matroska ChapterAtom. It does not set any
ChapterTrackNumber which means that the chapters all apply to all tracks in the file.
As this is a text file character set conversion may need to be done. See the section about text files and
character sets for an explanation how mkvmerge(1) converts between character sets.
The XML based chapter format
The XML based chapter format looks like this example:
<?xml version="1.0" encoding="ISO-8859-1"?>
<!DOCTYPE Chapters SYSTEM "matroskachapters.dtd">
<Chapters>
<EditionEntry>
<ChapterAtom>
<ChapterTimeStart>00:00:30.000</ChapterTimeStart>
<ChapterTimeEnd>00:01:20.000</ChapterTimeEnd>
<ChapterDisplay>
<ChapterString>A short chapter</ChapterString>
<ChapterLanguage>eng</ChapterLanguage>
</ChapterDisplay>
<ChapterAtom>
<ChapterTimeStart>00:00:46.000</ChapterTimeStart>
<ChapterTimeEnd>00:01:10.000</ChapterTimeEnd>
<ChapterDisplay>
<ChapterString>A part of that short chapter</ChapterString>
<ChapterLanguage>eng</ChapterLanguage>
</ChapterDisplay>
</ChapterAtom>
</ChapterAtom>
</EditionEntry>
</Chapters>
With this format three things are possible that are not possible with the simple chapter format:
1. The timestamp for the end of the chapter can be set,
2. chapters can be nested,
3. the language and country can be set.
The mkvtoolnix distribution contains some sample files in the doc subdirectory which can be used as a
basis.
The following lists the supported XML tags, their data types and, where appropriate, the valid range for
their values:
Chapters (master)
EditionEntry (master)
EditionUID (unsigned integer, valid range: 1 <= value)
EditionFlagHidden (unsigned integer, valid range: 0 <= value <= 1)
EditionFlagDefault (unsigned integer, valid range: 0 <= value <= 1)
EditionFlagOrdered (unsigned integer, valid range: 0 <= value <= 1)
ChapterAtom (master)
ChapterAtom (master)
ChapterUID (unsigned integer, valid range: 1 <= value)
ChapterTimeStart (unsigned integer)
ChapterTimeEnd (unsigned integer)
ChapterFlagHidden (unsigned integer, valid range: 0 <= value <= 1)
ChapterFlagEnabled (unsigned integer, valid range: 0 <= value <= 1)
ChapterSegmentUID (binary, valid range: 1 <= length in bytes)
ChapterSegmentEditionUID (unsigned integer, valid range: 1 <= value)
ChapterPhysicalEquiv (unsigned integer)
ChapterTrack (master)
ChapterTrackNumber (unsigned integer, valid range: 1 <= value)
ChapterDisplay (master)
ChapterString (UTF-8 string)
ChapterLanguage (UTF-8 string)
ChapterCountry (UTF-8 string)
ChapterProcess (master)
ChapterProcessCodecID (unsigned integer)
ChapterProcessPrivate (binary)
ChapterProcessCommand (master)
ChapterProcessTime (unsigned integer)
ChapterProcessData (binary)
General notes
When splitting files mkvmerge(1) will correctly adjust the chapters as well. This means that each file
only includes the chapter entries that apply to it, and that the timestamps will be offset to match the
new timestamps of each output file.
mkvmerge(1) is able to copy chapters from Matroska source files unless this is explicitly disabled with
the --no-chapters option. The chapters from all sources (Matroska files, Ogg files, MP4 files, chapter
text files) are usually not merged but end up in separate ChapterEditions. Only if chapters are read from
several Matroska or XML files that share the same edition UIDs will chapters be merged into a single
ChapterEdition. If such a merge is desired in other situations as well then the user has to extract the
chapters from all sources with mkvextract(1) first, merge the XML files manually and mux them afterwards.
TAGS
Introduction
Matroska's tag system is similar to that of other containers: a set of KEY=VALUE pairs. However, in
Matroska these tags can also be nested, and both the KEY and the VALUE are elements of their own. The
example file example-tags-2.xml shows how to use this system.
Scope of the tags
Matroska tags do not automatically apply to the complete file. They can, but they also may apply to
different parts of the file: to one or more tracks, to one or more chapters, or even to a combination of
both. The Matroska specification[5] gives more details about this fact.
One important fact is that tags are linked to tracks or chapters with the Targets Matroska tag element,
and that the UIDs used for this linking are not the track IDs mkvmerge(1) uses everywhere. Instead the
numbers used are the UIDs which mkvmerge(1) calculates automatically (if the track is taken from a file
format other than Matroska) or which are copied from the source file if the track's source file is a
Matroska file. Therefore it is difficult to know which UIDs to use in the tag file before the file is
handed over to mkvmerge(1).
mkvmerge(1) knows two options with which you can add tags to Matroska files: The --global-tags and the
--tags options. The difference is that the former option, --global-tags, will make the tags apply to the
complete file by removing any of those Targets elements mentioned above. The latter option, --tags,
automatically inserts the UID that mkvmerge(1) generates for the tag specified with the TID part of the
--tags option.
Example
Let's say that you want to add tags to a video track read from an AVI. mkvmerge --identify file.avi
tells you that the video track's ID (do not mix this ID with the UID!) is 0. So you create your tag file,
leave out all Targets elements and call mkvmerge(1):
$ mkvmerge -o file.mkv --tags 0:tags.xml file.avi
Tag file format
mkvmerge(1) supports a XML based tag file format. The format is very closely modeled after the Matroska
specification[5]. Both the binary and the source distributions of MKVToolNix come with a sample file
called example-tags-2.xml which simply lists all known tags and which can be used as a basis for real
life tag files.
The basics are:
• The outermost element must be <Tags>.
• One logical tag is contained inside one pair of <Tag> XML tags.
• White spaces directly before and after tag contents are ignored.
Data types
The new Matroska tagging system only knows two data types, a UTF-8 string and a binary type. The first is
used for the tag's name and the <String> element while the binary type is used for the <Binary> element.
As binary data itself would not fit into a XML file mkvmerge(1) supports two other methods of storing
binary data. If the contents of a XML tag starts with '@' then the following text is treated as a file
name. The corresponding file's content is copied into the Matroska element.
Otherwise the data is expected to be Base64 encoded. This is an encoding that transforms binary data into
a limited set of ASCII characters and is used e.g. in email programs. mkvextract(1) will output Base64
encoded data for binary elements.
The deprecated tagging system knows some more data types which can be found in the official Matroska tag
specs. As mkvmerge(1) does not support this system anymore these types aren't described here.
Known tags for the XML file format
The following lists the supported XML tags, their data types and, where appropriate, the valid range for
their values:
Tags (master)
Tag (master)
Targets (master)
TargetTypeValue (unsigned integer)
TargetType (UTF-8 string)
TrackUID (unsigned integer)
EditionUID (unsigned integer)
ChapterUID (unsigned integer)
AttachmentUID (unsigned integer)
Simple (master)
Simple (master)
Name (UTF-8 string)
TagLanguage (UTF-8 string)
DefaultLanguage (unsigned integer)
String (UTF-8 string)
Binary (binary)
THE SEGMENT INFO XML FILES
With a segment info XML file it is possible to set certain values in the "segment information" header
field of a Matroska file. All of these values cannot be set via other command line options.
Other "segment information" header fields can be set via command line options but not via the XML file.
This includes e.g. the --title and the --timestamp-scale options.
There are other elements that can be set neither via command line options nor via the XML files. These
include the following elements: DateUTC (also known as the "muxing date"), MuxingApp, WritingApp and
Duration. They're always set by mkvmerge(1) itself.
The following lists the supported XML tags, their data types and, where appropriate, the valid range for
their values:
Info (master)
SegmentUID (binary, valid range: length in bytes == 16)
SegmentFilename (UTF-8 string)
PreviousSegmentUID (binary, valid range: length in bytes == 16)
PreviousSegmentFilename (UTF-8 string)
NextSegmentUID (binary, valid range: length in bytes == 16)
NextSegmentFilename (UTF-8 string)
SegmentFamily (binary, valid range: length in bytes == 16)
ChapterTranslate (master)
ChapterTranslateEditionUID (unsigned integer)
ChapterTranslateCodec (unsigned integer)
ChapterTranslateID (binary)
MATROSKA FILE LAYOUT
The Matroska file layout is quite flexible. mkvmerge(1) will render a file in a predefined way. The
resulting file looks like this:
[EBML head] [segment {meta seek #1} [segment information] [track information] {attachments} {chapters}
[cluster 1] {cluster 2} ... {cluster n} {cues} {meta seek #2} {tags}]
The elements in curly braces are optional and depend on the contents and options used. A couple of notes:
• meta seek #1 includes only a small number of level 1 elements, and only if they actually exist:
attachments, chapters, cues, tags, meta seek #2. Older versions of mkvmerge(1) used to put the
clusters into this meta seek element as well. Therefore some imprecise guessing was necessary to
reserve enough space. It often failed. Now only the clusters are stored in meta seek #2, and meta
seek #1 refers to the meta seek element #2.
• Attachment, chapter and tag elements are only present if they were added.
The shortest possible Matroska file would look like this:
[EBML head] [segment [segment information] [track information] [cluster 1]]
This might be the case for audio-only files.
EXTERNAL TIMESTAMP FILES
mkvmerge(1) allows the user to chose the timestamps for a specific track himself. This can be used in
order to create files with variable frame rate video or include gaps in audio. A frame in this case is
the unit that mkvmerge(1) creates separately per Matroska block. For video this is exactly one frame, for
audio this is one packet of the specific audio type. E.g. for AC-3 this would be a packet containing 1536
samples.
Timestamp files that are used when tracks are appended to each other must only be specified for the first
part in a chain of tracks. For example if you append two files, v1.avi and v2.avi, and want to use
timestamps then your command line must look something like this:
$ mkvmerge ... --timestamps 0:my_timestamps.txt v1.avi +v2.avi
There are four formats that are recognized by mkvmerge(1). The first line always contains the version
number. Empty lines, lines containing only whitespace and lines beginning with '#' are ignored.
Timestamp file format v1
This format starts with the version line. The second line declares the default number of frames per
second. All following lines contain three numbers separated by commas: the start frame (0 is the first
frame), the end frame and the number of frames in this range. The FPS is a floating point number with the
dot '.' as the decimal point. The ranges can contain gaps for which the default FPS is used. An example:
# timestamp format v1
assume 27.930
800,1000,25
1500,1700,30
Timestamp file format v2
In this format each line contains a timestamp for the corresponding frame. This timestamp must be given
in millisecond precision. It can be a floating point number, but it doesn't have to be. You have to give
at least as many timestamp lines as there are frames in the track. The timestamps in this file must be
sorted. Example for 25fps:
# timestamp format v2
0
40
80
Timestamp file format v3
In this format each line contains a duration in seconds followed by an optional number of frames per
second. Both can be floating point numbers. If the number of frames per second is not present the default
one is used. For audio you should let the codec calculate the frame timestamps itself. For that you
should be using 0.0 as the number of frames per second. You can also create gaps in the stream by using
the 'gap' keyword followed by the duration of the gap. Example for an audio file:
# timestamp format v3
assume 0.0
25.325
7.530,38.236
gap, 10.050
2.000,38.236
Timestamp file format v4
This format is identical to the v2 format. The only difference is that the timestamps do not have to be
sorted. This format should almost never be used.
EXIT CODES
mkvmerge(1) exits with one of three exit codes:
• 0 -- This exit code means that muxing has completed successfully.
• 1 -- In this case mkvmerge(1) has output at least one warning, but muxing did continue. A warning is
prefixed with the text 'Warning:'. Depending on the issues involved the resulting file might be ok or
not. The user is urged to check both the warning and the resulting file.
• 2 -- This exit code is used after an error occurred. mkvmerge(1) aborts right after outputting the
error message. Error messages range from wrong command line arguments over read/write errors to
broken files.
ENVIRONMENT VARIABLES
mkvmerge(1) uses the default variables that determine the system's locale (e.g. LANG and the LC_*
family). Additional variables:
MKVMERGE_DEBUG, MKVTOOLNIX_DEBUG and its short form MTX_DEBUG
The content is treated as if it had been passed via the --debug option.
MKVMERGE_ENGAGE, MKVTOOLNIX_ENGAGE and its short form MTX_ENGAGE
The content is treated as if it had been passed via the --engage option.
SEE ALSO
mkvinfo(1), mkvextract(1), mkvpropedit(1), mkvtoolnix-gui(1)
WWW
The latest version can always be found at the MKVToolNix homepage[6].
AUTHOR
Moritz Bunkus <moritz@bunkus.org>
Developer
NOTES
1. the Matroska website
http://www.matroska.org/
2. the IANA homepage
http://www.iana.org/assignments/media-types/
3. mkvmerge-identification-output-schema-v12.json
https://mkvtoolnix.download/doc/mkvmerge-identification-output-schema-v12.json
4. RFC 7159
https://tools.ietf.org/html/rfc7159
5. Matroska specification
http://matroska.org/technical/specs/index.html
6. the MKVToolNix homepage
https://mkvtoolnix.download/